(Click to enlarge photo of Srila Prabhupada)
"Laulyam means just like we become very much greedy in achieving some success or receiving something sometimes. We become mad. That is required. Laulyam eka mūlyam. To achieve Kṛṣṇa consciousness perfectly, this ecstatic eagerness or greediness, to serve Kṛṣṇa, that is the only price to achieve success in devotional service. That is the only price. Not money, not anything. Not prestige, not good parentage, not beauty—nothing. Simply this ecstatic, intense desire, 'How I shall get Kṛṣṇa?' Then you'll get Kṛṣṇa. He'll take you.
That is the example of the gopīs, intense desire. Tatra laulyam eka mūlyam. Now, janma-koṭi, na labhyate janma-koṭibhiḥ sukṛtinaḥ. This ecstatic desire, that 'I, this life, I shall get recognition by Kṛṣṇa, that I have sacrificed everything for Kṛṣṇa,' this is required."
(Srila Prabhupada Lecture, Bombay, December 26, 1972)